Management of chylothorax

BACKGROUND: Chylothorax is a rare primary or secondary condition the optimum management of which remains uncertain. METHODS: Twenty cases of chylothorax, including ten of primary chylothorax and ten secondary to either malignancy, subclavian vein thrombosis or lymphangioma treated between 1956 and 1986 have been reviewed. RESULTS: Open pleurectomy was the most successful treatment in preventing reaccumulation of the effusion. Three patients had thoracic duct-azygous vein anastomoses, but all anastomoses were probably occluded within a year of surgery. Three patients have been lost to follow-up and five died within 2 years of their treatment, but 12 patients were alive and free from an effusion 3-22 years after treatment. CONCLUSION: Patients with chylothorax should undergo lymphangiography to identify the cause and site of the lymphatic abnormality. Conservative treatment is successful in some patients but should be abandoned if the fluid loss exceeds 1.5 l/day for more than 5-7 days in an adult or more than 100 ml/day in a child. Parietal pleurectomy is the most successful treatment when no distinct chylous leak can be identified. Less commonly, an isolated chylous leak either in the chest or in the abdomen may be identified and this should be treated by direct ligation.     

Rat insulinoma-derived pancreatic beta-cells express a functional leptin receptor that mediates a proliferative response

In addition to its interaction at hypothalamic sites to affect feeding and energy expenditure, leptin has been shown to exhibit a proliferative response in erythropoietic cells. The functional leptin receptor is also present in pancreatic islets and we now demonstrate that a commonly used clonal insulin secreting beta-cell line, RINm5F, expresses high levels of the Ob-Rb mRNA. Leptin causes an increase in tyrosine phosphorylation of a number of intracellular proteins and a dose related (10 nM-200 nM) increase in expression of the immediate-early gene, c-fos. This precedes a leptin induced proliferative response in serum-deprived RINm5F cells, which suggests that leptin might be involved in the complex regulation of proliferation of the pancreatic beta-cell.     

Vaccination and the population structure of antigenically diverse pathogens that exchange genetic material

Populations of antigenically diverse pathogens undergoing genetic exchange may be categorized into strains on the basis of a set of principal protective antigens. The extent to which polyvalent vaccines based on these protective antigens can alter the population structure of the pathogen is determined by the degree of cross-protection between strains. In the case where there is no cross-protection, vaccinating against a particular strain will have no effect on the others. As cross-protection increases, the strains containing the antigenic variants included in the vaccine will be diminished in prevalence, and those that do not will increase in prevalence. The rise in prevalence of the latter will become more and more exaggerated as cross-protection increases. However, beyond a critical level of cross-protection, in the absence of vaccination, the steady state of the system is asymmetric in that a certain subset of strains (with non-overlapping repertoires of antigenic variants) will dominate over the others in terms of prevalence. Under these circumstances, a vaccine consisting of the most immunogenic combinations of antigenic variants can cause a dramatic increase in frequency of a subset of rare strains.     

Agreement and clinical utility of 2 techniques for measuring cardiac output in patients with low cardiac output

BACKGROUND: The reliability of cardiac output obtained with the bolus technique is a problem. OBJECTIVES: To compare measurements of cardiac output measured with bolus and continuous techniques in patients with low cardiac output and to determine if measurements obtained with the continuous technique increased the number of subsequent clinical decisions. METHODS: In 60 intensive care patients, a nurse recorded a single continuous cardiac output measurement and then obtained the mean of 3 consecutive bolus determinations. The medical records of these 60 patients (experimental group) for the next 48 hours and of 60 other patients with regular or mixed venous oximetry catheters (control group) were reviewed to assess the occurrence of cardiac output events and the frequency of clinical decisions based on the events. RESULTS: Mean cardiac output was 4.46 L/min by the continuous technique and 5.20 L/min by the bolus technique (P = .011) for the experimental group. Median bias between the 2 types of measurements was -0.10 L/min (P = .79). Twenty-three of the pairs (38%) had an absolute percent difference greater than 15%. Of these, 18 (78%) had a higher bolus reading. Treatment decisions per 48 hours were 9.9 for the experimental group and 8.6 for the control group (P = .014). Median length of stay was 2 days less in the experimental group (P = .02), and mean highest cardiac output was 0.81 L/min higher (P = .009). CONCLUSIONS: Measurements of cardiac output determined with the continuous technique may be more precise than measurements determined with the bolus technique. Continuous cardiac output information increases the number of treatment decisions and actions that may shorten hospital length of stay.     

Dopamine D3 receptor mutant mice exhibit increased behavioral sensitivity to concurrent stimulation of D1 and D2 receptors

The dopamine D3 receptor is expressed primarily in regions of the brain that are thought to influence motivation and motor functions. To specify in vivo D3 receptor function, we generated mutant mice lacking this receptor. Our analysis indicates that in a novel environment, D3 mutant mice are transiently more active than wild-type mice, an effect not associated with anxiety state. Moreover, D3 mutant mice exhibit enhanced behavioral sensitivity to combined injections of D1 and D2 class receptor agonists, cocaine and amphetamine. However, the combined electrophysiological effects of the same D1 and D2 agonists on single neurons within the nucleus accumbens were not altered by the D3 receptor mutation. We conclude that one function of the D3 receptor is to modulate behaviors by inhibiting the cooperative effects of postsynaptic D1 and other D2 class receptors at systems level.     

Unusual fatty acid compositions of the hyperthermophilic archaeon Pyrococcus furiosus and the bacterium Thermotoga maritima

The fatty acid compositions of the hyperthermophilic microorganisms Thermotoga maritima and Pyrococcus furiosus were studied and compared. A total of 37 different fatty acids were identified in T. maritima, including the novel 13,14-dimethyloctacosanedioic acid. In contrast, a total of 18 different fatty acids were characterized, as minor components, in P. furiosus, and these included saturated, monounsaturated, and dicarboxylic acids. This is the first report of fatty acids from an archaeon.